Durham University Split SUSY at Colliders Peter Richardson

Durham University Split SUSY at Colliders Peter Richardson Work done in collaboration with W. Kilian, T. Plehn and E. Schmidt, Eur. Phys. J. C 39: 229 -243, 2005, hep-ph/0408088. Susy 05, Durham 21 st July 1

Introduction • We have had a lot of talks on Split SUSY and theoretical motivations (or lack of them. ) • I will not repeat those arguments now. • From a phenomenological point of view Split SUSY is interesting because it predicts very different collider signatures. • We need to investigate these signatures to ensure we don't miss SUSY if it’s there. Susy 05, Durham 21 st July 2

Introduction • In Split SUSY due to the high mass scale the only SUSY particles which can be produced in colliders are – Gluinos – Charginos – Neutralinos Susy 05, Durham 21 st July 3

Hadron Collider Signals • At hadron colliders the only production mechanisms are – Gluino pairs – Gaugino pairs due to the large scalar masses associated production mechanisms are negligible. • The signals from the gauginos may be observable but it is hard at both the Tevatron and LHC unless the masses are close to the LEP limits. Susy 05, Durham 21 st July 4

Gauginos at Hadron Colliders • For a sample Split SUSY point with • The masses are Susy 05, Durham 21 st July 5

Gauginos at Hadron Colliders • The dominant cross sections are – – – 2910 fb 1498 fb 2099 fb • The trilepton signal is hard as the decay is mediated by the Z. • Other modes might be possible. Susy 05, Durham 21 st July 6

Gluinos at Hadron Colliders • • • There is however a large cross section for the production of gluino pairs. In the Split SUSY model this only depends on the mass of the gluino. There are three scenarios 1) Gluino decays promptly 2) Gluino decays in the detector. 3) Gluino is stable on collider timescales Susy 05, Durham 21 st July 7

Gluinos at Hadron Colliders • The first two scenarios should be similar to the models already studied, with the addition of displaced vertices in the second case. • Therefore we studied the case of the stable gluino. • There have been previous studies of this for the Tevatron Baer, Cheung, Gunion PRD 59, 075002 and we used many of the same ideas. Susy 05, Durham 21 st July 8

Gluinos at Hadron Colliders • When the gluino hadronizes it will form either – Glueball-like state – Mesonic state – Baryonic state • General opinion is that – Rg is the lightest state – Rqqq is unlikely to be directly produced. Susy 05, Durham 21 st July 9

Gluinos at Hadron Colliders • We included the production of these states in the cluster hadronization model of HERWIG. • Due to the modelling of the hadronization the relative probability, , , of producing the gluonic and mesonic R-hadrons is undetermined. • This parameter and the gluino mass determined the phenomenology at hadron colliders. Susy 05, Durham 21 st July 10

Gluinos at Hadron Colliders • There are two signals we considered • Charged R-hadron production – Signal much like stable weakly interacting particles. – R-hadron looks like a muon but deposits more energy in the calorimeter. – Arrives later at the muon chambers due to the mass. – Can measure the mass using the time-delay. Susy 05, Durham 21 st July 11

Gluinos at Hadron Colliders • Neutral R-hadron production – Some energy loss in calorimeter – Monojet type signals • In both cases we used HERWIG interfaced to Acer. Det for fast detector simulation together with simple modelling of the Rhadron interactions based on Baer, Cheung, Gunion PRD 59, 075002. Susy 05, Durham 21 st July 12

Energy Loss • We used a range of different models of the hadronic cross section to estimate the uncertainty of this simple approach. • The more accurate results of Kraan hepex/0404001 are within this range. Susy 05, Durham 21 st July 13

Energy Loss Susy 05, Durham 21 st July 14

Charged R-hadrons • Applied a simple efficiency for reconstruction for 85% as with muons. • Required the charged R-hadron to have transverse momentum greater than 50 Ge. V. • The time delay at the muon detectors between 10 ns and 50 ns. • Required the observation of 10 events. Susy 05, Durham 21 st July 15

5, Durham 21 st July Charged R-hadrons

Mass Measurement Susy 05, Durham 21 st July 17

Durham 21 st July Mass Measurement

Neutral Searches • The neutral search was based on an optimised analysis using the same cuts as the experimental analysis in Barr et. al. JHEP 0303: 045, 2003. • This requires at least 100 Ge. V missing transverse energy and one jet with transverse momentum greater than 100 Ge. V which should be sufficient to pass the trigger. Susy 05, Durham 21 st July 19

Neutral Searches

LHC • Charged R-hadron signal can be seen up to above 2 Te. V. • Neutral signal is worse. • Needs more detailed experimental study. • There have been other studies • Hewett et. al. JHEP 0409: 070, 2004 considered the charge flipping which we neglected. • STOPPING GLUINOS. • Arvanitaki et. al. hep-ph/0506242 consider gluinos which are stopped in the detector. Susy 05, Durham 21 st July 21

ILC • Chargino and Neutralino sector is the same as usual. • Masses can be extracted using standard techniques. • The integrating out of the heavy degrees of freedom leads to different neutral/chargino Yukawa couplings. Susy 05, Durham 21 st July 22

ILC • • Assume mass measurements to 0. 5% Cross sections with statistical error only. Fit the anomalous Yukawa couplings. At larger values possible to distinguish weakscale MSSM from Sp. S. Susy 05, Durham 21 st July 23

Conclusions • Split SUSY has different and interesting experimental signals. • Should be observable at the LHC for gluino masses less than 2 Te. V. • At a linear collider can be verified by looking at gaugino yukawa couplings. • In general looking at the gaugino yukawa couplings would be an interesting test of the MSSM. Susy 05, Durham 21 st July 24